The concept of heat pipes has been extended to plate-type heat pipes (two-dimensional) and even heat pipe steam chamber (three-dimensional). Currently, for meeting the requirement of special thermal control applications, the outline and inner space of the heat pipes to be designed are continuously increasing, and the demand for plate-type heat pipes and the heat pipe steam chamber with a large filling volume is continuously increasing.
High-temperature heat pipes (when a working temperature reaches 500 degrees Celsius or is greater than 500 degrees Celsius) and ultra-high temperature heat pipes (when a working temperature reaches 1200 degrees Celsius or is greater than 1200 degrees Celsius) generally employ alkali metal, lead, silver, etc. as a working medium. Most of these working media are in a solid state at a normal temperature, and some of these working media are extremely easily oxidized. Under normal conditions, the alkali metal working media are in a solid state at the normal temperature and are easily oxidized even in poor oxygen conditions, thus inert gas protection is very important in the technical process. In addition, different alkali metals have different melting points, thus imposing increasingly high requirements on filling of the working media. Under the condition of the conventional heat pipe process technology, filling methods in the conventional technology cannot meet the requirements of heat pipe filling such as a stable process, non-oxidation, a large range, a precise quantitative filling and a convenient operation.
In the process of alkali metal split charging, it should be ensured that: the heat pipe has a sufficiently high vacuum degree; and a quantity of the working medium filled can be controlled; the working medium filled has a high purity, that is, meets the requirements of high purity working medium. For ultra-high temperature heat pipes, for example, taking lithium as the working medium, the previous split charging methods for alkali metals such as sodium, potassium are not applicable any more, which demonstrates in aspects that the filling process is not sufficiently stable, the filling method is not adaptable to filling heat pipes with a large filling range, the post-treatment is troublesome, and the heat pipes filled have a short service life. In respect of filling heat pipes with sodium, there are four typical conventional filling technologies as follows.
(1) The process for distilling and filling metallic sodium, for example, the document “HEAT PIPE written by Ma Tongze, Hou Zengqi, Wu Wenguang published in 1991 by Science Press with ISBN 7-03-002011-1 on pages 277 to 282” introduces a method for distilling and filling sodium, as shown in FIG. 1. In this distillation process method, the process changes of alkali metal are controlled to be from solid state→liquid state→gaseous state→liquid state→solid state. The process and device are complex, a long time is consumed, the post-treatment is troublesome, and precise quantitative filling is difficult to be achieved.
(2) A quantitative filling device and method of solid alkali metal working media (invented by Qu Wei and Yu Bin with Application No. 200910091897.2) is as shown in FIG. 2. This method uses a filtering process, and the process changes of alkali metal are controlled to be from solid state→liquid state→liquid state→solid state. Compared with the method described in Technology (1), the process is simpler, however, since exhausted gas of the connected heat pipe needs to pass through the working medium, a vacuum resistance is large and the vacuum degree required is not easy to reach. In addition, a vacuum glove cartridge falls into an open inert gas protection, a small part of alkali metal is still oxidized during the split charging process, which may adversely affect the final performance of the heat pipe.
(3) An accurate filling equipment and method for high temperature heat pipe requiring small amount of alkali metal working medium (invented by Qu Wei, Duan Yanjun with Application No. 201110088089) is as shown in FIG. 3. Compared with the method described in Technology (2), a bypass structure is adopted, and a heating device is embodied as a peripheral heating belt. Due to using the heating belt to peripherally heat, the method for winding the heating belt has a significant effect on the temperature control, and the process is not sufficiently stable. Further, the winding process is troublesome, an insulation material of the heating belt used is volatile, which may have an adverse effect on operators. In addition, the vacuum glove cartridge falls into the open inert gas protection, there is still a small part of the alkali metal oxidized during the split charging, which also restricts the improvement of final performance of the heat pipe.
(4) An non-Oxidation split charging method and integrated device for alkali metal working medium (invented by Qu Wei, Ai Bangcheng, Yu Jijun, Xue Zhihu with Application No. 201210378002.5) is as shown in FIG. 4. Compared with the method described in Technology (3), four suction-exhaust pipes are employed inside the glove box, and gas exhaust and suction of each pipe to two corner areas where the pipe passes is not uniform enough. A built-in balance occupies most of the space inside the glove box, and a filling quantity defined by the process method and device is also not large. A wall surface of the process tank has a complex structure, which is not easy to assemble and disassemble. Reference numerals in FIG. 4 are described as follows: 101 working medium tank, 102 glove box upper cover (transparent), 103 main intake pipe (inert gas), 104 first ultrahigh vacuum sealing valve, 105 second ultrahigh vacuum sealing valve, 106 third ultrahigh vacuum sealing valve, 107 ultrahigh-vacuum molecular pump set, 108 fourth intake valve, 109 first intake pipe, 110 fifth intake valve, 111 sixth intake valve, 112 seventh exhaust valve, 201 working medium tank, 205 cooling water inlet, 206 cooling water outlet, 208 screw hole for fixing heating rod, 209 working medium tank sealing lower flange, 210 sealing grid, 211 working medium tank sealing upper flange, 212 branch air suction bypass, 213 branch inert gas intake bypass, 301 glove operation box, 302 glove opening, and 303 exhaust manifold.